This invention relates to a mixing device for an aircraft air conditioning system with a supply conduit for fresh air from the air conditioning system, with a second supply conduit for recirculated air from a pressurized region of the aircraft, and with a discharge conduit for supplying mixed air into the pressurized region of the aircraft.
Aircraft air conditioning systems serve to provide conditioned air for the various regions of the aircraft, for instance for the aircraft cabin or for the cockpit.
In particular, this invention now relates to a component for mixing and/or dividing various streams of air. In the process, fresh air from the air conditioning system is mixed with air from the aircraft cabin and recirculated to the cabin via a distribution system.
Under normal circumstances, the problem arises that all components which protrude into the flow will ice under operating conditions in which the air is very cold and saturated with moisture.
To solve this problem, it has already become known from U.S. Pat. No. 6,971,607 B2 to enclose a first supply conduit for fresh air from the air conditioning system with a second supply conduit for recirculated air from the aircraft cabin in its terminal region, wherein both supply conduits open into a discharge conduit for supplying mixed air into the aircraft cabin. Comparatively warm recirculated air from the aircraft cabin thus surrounds the cold fresh air flowing out of the air conditioning system, so that icing as a result of the heat transfer from the warm air can be prevented. The discharge conduit for supplying fresh air into the cockpit branches off from the first supply conduit for fresh air from the air conditioning system. This results in a very complex component for the mixing chamber.
From the non-prepublished German patent application 10 2007 002 138.2 a mixing device for aircraft air conditioning systems is already known, which consists of pockets arranged one above the other in flow cross-section, which partly have a free cross-section and partly include a diagonal partition.
As shown in FIG. 1, premixing cold fresh air from the air conditioning system with warm circulating air from the cabin conventionally has so far been effected in the unpressurized region in the aircraft. For this purpose, the warm circulating air is passed from the cabin through the so-called pressure bulkhead into the unpressurized region. The mixed, ice-free air is recirculated to the cabin via a non-return flap. To maintain the cabin pressure in a case of error, i.e. for instance in the case of a conduit breaking in the unpressurized region, the circulating air conduit in the pressure bulkhead is closed by a further safety valve. In this variant, the non-return flap is provided downstream of the mixer, so that the non-return flap is supplied with warmer mixed air as compared to the cold fresh air and thus remains ice-free.
However, the solution as described above leads to a rather complex construction, as on the one hand a safety valve and on the other hand a non-return flap must be provided in the pressure bulkhead as separate components.